There are known in the prior art merchandising machines which, in response to the deposit therein of a sum of money and the operation of a selecting mechanism, deliver to the customer a cold drink which may or may not, at the customer's option, include a quantity of ice. The control systems of these machines of the prior art include an electromechanical timer and associated electromechanical relays for operating the various pumps and valves of the machine.
While the cold drink merchandising machine control systems of the type described above are generally effective in providing the desired operation of the machine, they suffer from a number of disadvantages. The electromechanical components are relatively expensive. The timing afforded by the control system is relatively imprecise. Many of the settings required to be made in the control system are analogue in nature and thus relatively difficult for the service personnel. Since the machines operate on a constant time variable flow rate mode of operation, a change in the drink size requires a relatively difficult adjustment of the valve flow rate. Moreover, changing of a selection among highly carbonated, low carbonated and plain, necessitates a wiring change.